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Old 10-13-2021, 01:52 PM   #1
tmhobadcap
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Join Date: Apr 2019
City & State: Richmond, BC
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Default LG 24MP56HQ-P Monitor Backlight problem?

I have a few successful experience in fixing tv backlight problem. But for monitor, I have no experience. However, I think they are more or less the same. Am I correct?

Recently, I got the captioned monitor and the owner said it could not be turned on. I open it up and found that one of the SMT capacitors seemed to be bad. I replaced it as well as the other one. The monitor still could not be turned on.

I found the power indicator is on. When I shine a flashlight on the screen, I can see the image. Therefore, I think it is with backlight problem. I took out the led strip. I tested all leds individually and in groups (they are divided into 3 groups) and they all can be lighted up. I have also tested all the connections and they are also good.

There are six wires connecting from the mainboard to the led strips. With the blue (edited) wire as the first wire, I found the 3rd and the 4th with 19V and all other with 0V. From the connector of the led strip, I found the 3rd and the 4th wires are connected and connect to one end of each of the three groups of leds. The 1st, 2nd and 6th wires are connected to the other ends of the three groups of leds. The 5th wire just has no connection to the leds. One group of led has 16 leds and so 19V is not high enough to light up the group.

Is this a backlight problem? According to the trouble shooting section of the manual, if no image is shown on the screen, we should check the brightness and contrast. But when I press the menu button, I could not get the menu on screen to check the brightness and contract, nor to go to reset.

Can somebody please help me to fix this monitor?
Attached Images
File Type: jpg IMG_5437.jpg (461.7 KB, 11 views)
File Type: jpg IMG_5378.jpg (871.5 KB, 8 views)
File Type: jpg IMG_5435.jpg (702.2 KB, 7 views)
File Type: jpg IMG_5433.jpg (965.8 KB, 9 views)
File Type: jpg IMG_5429.jpg (397.7 KB, 9 views)

Last edited by tmhobadcap; 10-13-2021 at 01:56 PM..
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